Field of Invention
The present invention relates to an inductor structure and a manufacturing method thereof.
Description of Related Art
A conventional inductor structure may include a silicon substrate and plural copper bumps. The silicon substrate has plural bond pads. The copper bumps are respectively formed on the bond pads by electrolytic deposition, and have high frequency transmission performance. In subsequent process to the formation of the bumps, a ball grid array (BGA) or conductive protruding blocks may be electrically connected to the bond pads of the silicon substrate by the copper bumps. In that tin material and lead material cannot be directly adhered to the copper bumps, after the copper bumps are completely formed by electrolytic deposition, a nickel layer and a gold layer need to be formed in sequence by electrolytic deposition. The nickel layer has high impedance property to prevent the gold layer and the copper bump from fusing in high temperature ambience, while the gold layer can prevent the copper bump from oxidation.
The BGA or the conductive protruding blocks can be adhered to the copper bumps through the nickel layers and the gold layers, but, in fact, only the small number of the copper bumps in the inductor structure need to be electrically connected to the conductive protruding blocks or the BGA during the subsequent process, such as a bumping process or a BGA process, and most of the copper bumps do not need to be electrically connected to the BGA or the conductive protruding blocks. However, in general, when the inductor structure is manufactured, all of the copper bumps are formed with the nickel layers and the gold layers by electrolytic deposition due to limited process capability.
In this regard, the materials (e.g., gold) are wasted, and the unnecessary nickel layers and the gold layers formed on all of the copper bumps by electrolytic deposition increase the total resistance of the lines of the inductor structure and reduce the efficiency of the inductor structure. As such, the inductance of the inductor structure is difficultly improved.